King of the Ice Planets
Another confusing quirk is the magnetic field, which does not originate from the planet's geometric center due to the planet's tilted axis (at 59°)...and although I don't like quoting Wikipedia, they explained it well, stating that "The magnetic dipole is shifted from the center of the planet towards the south rotational pole by as much as one third of the planetary radius. This unusual geometry results in a highly asymmetric magnetosphere," http://en.wikipedia.org/wiki/Uranus#Magnetic_field. In other words the planet itself is much more tilted than your average planet, and due to this asymmetric geometry it also has an asymmetric magnetosphere. At the very least it makes sense, since the two correlate.
The water mass of Uranus alone is roughly 9.3-13.5 Earth-masses and the overall mass is around 14.5 Earth masses, where the remaining mass consists mostly of some rocky materials and other gases like helium and hydrogen. Of note, though, is that for a planet that is 14.5x more massive than Earth it is only around 99,787.21 miles in circumference around the equator (160,591.9 km), making it only about 4x the "size" of Earth even though it's mass might lead you to think it's far larger. This is probably because it is basically a frozen planet, where even its center is considered somewhat cool. For new readers of astronomy, when it comes to mass and size, just think of how many Earth's can fit inside the planet when astronomers say "masses," yet this is not the same thing as size, since Uranus is clearly many times more massive than Earth, yet it's overall size could not fit 14.5 Earth's inside of it- only 4, actually. This is because an object's mass in outer space also correlates to its density, causing something very large to be mushed even smaller, making size deceiving. This is what makes astronomy so much fun, because quirks like these really pull people out of what I call "Earth thinking," for what goes up does not always come down in astronomy. No-thing cannot be explained, however for in astronomy a person can always count on finding an adequate, sensible but often abstract answer, since Earth is very unique in the cosmos. For more on gravity or black holes, read my article on Black holes and Gravity.
Keep up with Nasa.gov because there's so much more to learn!